Negative Transfer During Autoinjector Use: Common Issues

By Alexandria Carlson  

The demand for medication to be delivered using autoinjectors is rising internationally, responding to the increased incidence rates of chronic conditions and the emerging treatments for those chronic conditions. Autoinjectors are used to deliver medication to treat Rheumatoid Arthritis, Multiple Sclerosis, Anaphylaxis, Crohn’s Disease, among others. It is reasonable to assume that some autoinjector users will have previously used syringes, pen-injectors or other types of autoinjectors (e.g., emergency-use autoinjectors).  

The challenge of negative transfer in device use 

Negative transfer is a potential cause of use errors and difficulties during device interactions. Negative transfer occurs when a user assumes how a device is going to work based on their experience with similar devices or similar device components. Below, we consider the negative transfer these individuals could experience when using autoinjectors.   

Negative transfer considerations for syringes 

Individuals who have experience using syringes might experience negative transfer when using autoinjectors. For example: 

• Cap removal. Autoinjectors might or might not have caps that users must remove before using the autoinjector, whereas users must always manually remove syringe caps to expose the syringe needle. Syringe-experienced users sometimes look for or attempt to remove a component of the autoinjector expecting to need to remove a cap. In the worst-case scenario, doing so could inadvertently activate the autoinjector.  

• Injection force. Inserting a syringe needle requires limited force, whereas depressing an autoinjector against the skin might require moderate force to activate the injection. Syringe-experienced users might not readily use enough force to activate the injection when using an autoinjector, which in some cases could even cause the autoinjector to lock the needle cover, preventing users from completing their injection.   

• Injection duration. Syringe users can more readily control the speed at which their injection is delivered and might be accustomed to delivering their injections quite quickly. As a result, they sometimes do not hold autoinjectors against their skin for a sufficient duration to deliver the injection.  Negative transfer considerations for pen-injectors 

Negative transfer considerations for pen-injectors

Individuals who have experience using pen-injectors might experience negative transfer when using auto-injectors. For example: 

• Needle cover appearance. Some autoinjectors have colored needle covers, and pen-injectors have colored needle covers or colored buttons on the backside of the pen-injector. Depending on what particular injection devices they have used previously, users might incorrectly identify the device’s needle cover as a button (or vice versa) and attempt to deliver an injection with the needle pointed away from their skin. Orienting the autoinjector incorrectly could lead to wasted medication or the user unintentionally injecting their finger.  

• Single- versus multi-use. Many pen-injectors contain multiple doses of medication, whereas most autoinjectors only contain one dose of medication. Pen-injector experienced users sometimes attempt to re-use autoinjectors based on their pen-injector experience. 

Negative transfer considerations for autoinjectors 

Individuals who have experience using emergency-use autoinjectors might experience negative transfer when using non-emergency use autoinjectors. For example: 

• Inspection. Some emergency-use autoinjectors such as the EpiPen do not have a viewing window for users to inspect the medication before use, in part because the device’s use is time-sensitive. Accordingly, users who are accustomed to emergency-use autoinjectors might not readily inspect the medication in non-emergency use autoinjectors for particles, cloudiness or discoloration. 

• Cleaning. Individuals who have needed to use emergency-use autoinjectors might have only used such devices in emergency, fast-paced situations. In these scenarios, users are unlikely to clean the injection site or wash their hands before delivering an injection. Accordingly, when using a non-emergency autoinjector, these users might not take these steps. 

• Injection site. Users are expected to administer the EpiPen to themselves or someone else in the thigh as soon as possible, even if they inject through clothing. When using a non-emergency autoinjector, EpiPen-experienced users could attempt to deliver the injection through their clothing. 

By considering these opportunities for negative transfer and addressing them proactively in a product’s design, manufacturers can support the safe and effective use of their products by users with prior injection device experience.  

Contact our team to learn more about how users’ backgrounds could impact product use. Or, sign up for a complimentary account with OPUS, our team’s software platform that provides HFE training, tools and templates. 

Alexandria Carlson is a lead human factors specialist at Emergo by UL.